Resilient piston



Oct. 4, 1932. c. MELIDONI REsiLIENT PISTON Filed Dec. 21. 1927 2Sheets-Sheet l v lNVENTOR g OA J TVV 77/VE MEL/00A ATTORNEY Oct. 4,1932. c. MELIDONI RESILIENT PISTCN Filed Dec. 21. 1927 2 Sheets-Sheet 2INVENTOR gONS WW5 MEL/00A 6 AT"TORNEY Patented Oct. 4, 1932 PATENTOFFICE CONSTANTINE MELIDONI, OF NEW YORK, 11'. Y.

BESILIEN'I. PISTON Application filed December 21, 1927. Serial No.241,637.

This invention relates to pistons used for internal combustion enginesand all kinds of engines in general, and the primary object of thisinvention is to provide a piston construction having skirt sectionswhich are extremely resilient in a radial direction so as to conformitself to the cylinder walls regardless of their worn or taperedcondition and which will operate without clearance space between thesesections and the cylinder wall and thereby prevent piston slap.

Another object of this invention is to provide a piston having in twoopposite sides of the piston skirt a series of longitudinal slots whichterminate alternately at lateral slots Within the piston skirt thusforming resilient sections which are over-cylinder-size. When theseresilient sections of the piston are compressed they react and exert anoutward pressure against the cylinder wall thereby centering andsupporting the piston within the cylinder.

Another object of this invention is to provide a piston with resilientsections, having a wear-compensating expanding action in order tomaintain contact with the cylinder wall at all times regardless of wearand which can be periodically restored to their original operatingdiameter.

Another object of this invention is to produce a resilient piston havingtherein two oppositely placed series of parallel and substantiallylongitudinal slots which are cut through the piston from the outer tothe inner circumferences and which will also have a solid head and asolid lower skirt section so that this resilient piston will present theappearance of solidity of the pistons in general use at present.

It is well known among those skilled in the internal combustion enginepiston art that as a piston approaches each end of the stroke there is aforce exerted which tends to move the piston laterally, resulting in atendency to vibrate and cause piston slap. Attempts to counteract thispiston slap and the noisy annoying clanking sounds have so far met withresults which were not of a permanent nature. It has been customary tosplit the piston skirt by a substantially longitudinal slot whichextended from the bottom edge of the skirt to a lateral slot below thelower ring groove. lVhen this type of piston is made over-cylinder-sizeand compressed so as to enter the cylinder, the center line of thepiston bosses is thrown out of line and makes it impossible for thepiston circumference to assume the contour of a perfect circle. Pistonsof such construction wear out the same as the ordinary solid pistons doand have a limited life and do not fully meet the demand of theautomotive industry for a replacement piston having extreme resilientproperties and the service life of which shall at the same time beperiodically restorable.

The problem consists in building a piston for an internal combustionengine with sections of the skirt made resilient and larger than thecylinder diameter and which could be compressed when entering thecylinder so that the piston skirt would fit tightly and the resilientsections of the piston would operate without the usual clearance of oneonethousandth of an inch per inch of piston diameter.

The solution of this problem is rendered diflicult by reason of the hightemperature in an internal combustion engine and the distortion of thecylinder by the expansion of the upper end of the cylinder under theheat so that the cylinder becomes an inverted frustum of a cone ratherthan a cylinder and that the piston when used under such operatingconditions must be free to follow the tapering cylinder walls with eachstroke of the piston. The skirt of the piston must be able to open upwhen the large diameter is reached and to close when the small diameteris reached and be subjected to an alternate outward and inward breathingaction for each stroke of the piston. A piston structure that will meetthese conditions must contain surfaces resiliently engageable with thecylinder wall at all times and regardless of the expansion orcontraction of the working parts due to temperature changes.

In solving this problem I endeavored to combine these features in apiston of prac tical type having the above noted and desirablecharacteristics embodied in a simple structure.

'ith the above objects in "low the invention will be hereinafter moreparticularly described. and the combination and arrangement of partswill be shown in the accompanying drawings and pointed out in the claimswhich form part of this specification. It being understood that variouschanges in the form, proportion, size and minor details of constructionwithin the scope of the claims, may be resorted to without departingfrom the spirit or sacrificing any of the advantages of the invention.

Reference will now be had to the drawings, wherein like numerals ofreference designate corresponding parts throughout the several views, inwhich:

Figure 1 is a front elevation of a resilient piston constructed inaccordance with this invention.

Figure 2 is a bottom view of the piston.

Figure 3 is a view of a corrugated semicircular spring.

Figure 4 is a vertical section of the piston, the section being taken ason line wm in Figure 2.

Figure 5 is a section of the piston, the section being taken as on line7 -g in Figure 4.

As shown in Figure 1, the piston illustrating this invention has theappearance of the usual stock piston. the skirt 1 of which has beenprovided with a plurality of longitudinal slots extending from the outerto the inner circumference of the piston.

As best shown in Figure 5, these slots 2, 3, 4, 5 and G, 7, 8, arelocated at a point diametrically perpendicular to the centre line of thewrist pin hole 9. A similar set of slots is located at the oppositepoint of the circumference. As best shown in Figure 4, there is alaterally cut slot 13 through the skirt on the cylindrical surface belowthe lower ring groove 12. Another lateral slot 14 is located in the sameplane on the opposite side of the piston circumference. There are alsoprovided two similar slots 15 and 16 which are located at the lower endof the piston skirt. These through slots are spaced in parallel planeswithin the piston skirt and form between them a plurality of spring barswhich are integral with each other and with the skirt. The four slots13, 15 and 14, 16 separate the spring bars between them respectivelyinto independent resilient sections 10 and 11. The curved outer surfacesof these resilient sections are free to assume the contour of a largercircumference upon the application of a pressure from within the pistonoutwardly and against the spring bars. The slots in section 10 arelocated opposite the corresponding slots-of section 11.

As best shown in Fig. 2, the interior of the piston is provided with twosemi-circular ring sections 23 and 24 to form open semicircular channels25 and 26 between these ring sections and the skirt. There are alsoprovided two corrugated semi-circular springs 27 which seat within thesemi-circular channels 25 and 26 and press outwardly against andre-enforce the spring bars of the two opposed resilient sections 10 and11 and hold the bars firmly .in place against the cylinder wall, thusmoulding the resilient skirt sections and forcing them to assume thecontour of the slightly larger size circle of the cylinder walls. Thecorrugations'of the springs have the effect of centering the pistonwithin the larger size circle of the rissilient sections, thuspreventing piston s ap.

As best shown in Fig. 4, the semi-circular ring sections 23 and 24 arein the same plane as the centre line of the bosses and are preferablyplaced at the middle of the longitudinal dimension of the spring bars.The width of the corrugated springs is preferably onequarter of an inchand the semi-circular ring sections are preferably provided with aonequarter inch wide annular groove 28 at their outer circumferentialfaces, so as to allow the springs to seat therein and prevent them fromfalling out when subjected to vibration. The annular grooves preferablytaper at their lower edges so as to facilitate the removal of thesprings. In addition to the grooves 28, there is a recess 29 at each endof the open semi-circular channels and these serve as a seat for eachend of the spring 27. The spring bars are integral with multiple unit ofbars which are capable of radial compression and expansion withoutdistorting the lateral planes or the continuity of any of the surfaceswhere the spring bars join the solid skirt and this arrangement preventsbuckling and crystallization.

The resilient sections 10 and 11 are preferably formed originally of adiameter greater than that of the cylinder and the remaining pistonsurfaces between these sections are relieved or ground down to cylindersize. The two resilient sections are then compressed sutficiently topermit the entrance of the piston into the cylinder. However, as bestshown in Fig. 4 the complete piston including the resilient sections 10and 11, the head 30 and a circumferentially intact section 31 'at thelower end of the piston skirt may be originally of cylinder sizethroughout and the springs 27 inserted within the piston skirt to exertan outward pressure against the resilient sections thereby forcing themto expand to a slightly larger diameter than the original piston. Theresilient sections are shown in Fig. 2, in an exaggerted oversizeposition. Under actual operating conditions, the oversize is of so smalla nature as to be hardly noticeable.

Particular attention is stressed to the fact that under all operatingconditions in the each other and form a cylinder the resilient sections10 and 11 maintain their over-eylinder-size while the rest of the pistonis about three thousandths of an inch under-cyliiider-size. Theoperating diameter of the two resilient sections of this piston beinglarger than that of the cylinder for which it is to be used, apredetermined pressure is developed between the two resilient sectionsand the wall of the cylinder, and this pressure is variable and islimited so as to permit the reciprocating movement of the piston in thecylinder under working conditions without any scoring or seizing actionand without any undue wear of the working parts. \Vhen the bearing sur-I faces of the two resilient sections 10 and 11 are finally worn downthe springs 27 are inserted inside the two semi-circular channels 25 and26. These springs press out the resilbe reversed and there will then befour longitudinal slots opening into the lower lateral slots 15 and 16.

In operation when the resilient sections 10 and 11 are compressed andthe metal is brought under tension, there is a reaction and a tendencyto expand to their original diameter and when the piston is inserted inan outof-round cylinder each section yields and conforms itself to theshape of the walls in badly worn cylinders where a perfect circle pistonwould be absolutely useless. The resilient sections absorb theside-thrust which ordinarily causes side-slap or piston-slap.

It is to be noted that while in Figures 1 to 5, inclusive, theillustrations show this pistion as equipped with means for re-enforcingand restoring the spring bars, the piston may if desired be formedwithout the semicircular ring sections 23 and 24 and the resilientsections may be made over-cylinder-size and thus function without there-enforcing effect of the springs 27.

It is also to be noted that the corrugated spring 27 is so formed thatthe circumferences of the outer and inner corrugations are concentric,that the corrugations are wider at the outer circumference 32 andnarrower at the inner circumference 33; also that both ends of thespring 34, 34, are reversely curved so as to form means for locking bothends of the spring in the recesses 29, 29.

When this slotted piston reaches the lower end of the cylinder the oilthrown into the skirt of the piston passes through the slots pressure.

and'lubricates the cylinder wall. This piston structure 'islthu sadapted to convey oil between the inner .andouter circumferences of thepiston andtakes care of excessive wall Pistons constructed according tothe subject matter of this invention may. be made either of cast irono rof aluminum alloys or of any other metal and are adapted for use innewgor reground icylinders and for worn cylinders. I The, 'pistojisltnay bev used extensively for replacement"purposes on automobile iii'otors,- and,;inay ;liave.to operate in worn out cylinders havijng taperingwalls generally smaller in dia nietler at the lower end of the cylinder.:Wheh th e'pistonrea ches the smaller diametei fof the cylinder thetwort silient sections gof the piston i 2 compressed and theinetalrec edesinternally within the piston. lVhen the la'r ia-ineten is re ached theresilient sections-expand toj't'he'larger diameter and the operationhisin a :sort of breathing action l'i i I have demonstrated fby actiialpractice that a piston embodying featureswof this invention and ofoyer-cylinder-si zegcan operate successfully: under fi'v'ofrkingfl'conditions and that it fitsfan d con w itself immediately to anyoncliti i Iii a ildiout-ofround cylinder withot t iiy distortion of thebosses or of the spriii ba r s' i It is" thus .readily' see Ythat the-rehas been provided a resilient lf fconfo rining piston with awear-compensatingexpanding action;

the bearing 'surfac e'so periodi- Cally restored. ta'th eirpjri' iah.ope'rating diameter, a'piston having anxtraordinary service life, apiston which will eliminate the annoyance caused by piston slap andwhich will have a substantially solid appearance and the cost of whichis within the limits of commercial requirements.

Having thus described my invention I claim as new and desire to secureby Letters Patent:

1. A resilient single piece piston comprising a head having piston ringgrooves upon its periphery and a skirt provided with wrist pin bossesand being integrally connected with the head between said bosses, theskirt being provided with two oppositely disposed series of parallelthrough slots longitudinally placed and terminated within the piston bytwo lateral through slots.

2. A resilient single piece piston comprising a head having piston ringgrooves upon its periphery and a skirt provided with wrist pin bossesand being integrally connected with the head between said bosses, theskirt being provided with two oppositely disposed series of parallelthrough slots longitudinally placed and terminated within the piston bylateral through slots, forming two resilient bearing sections ofover-cylinder-size, whereby when the piston is inserted in the cylinderIll) the over-eylinder-size sections are under tension and bear againstthe cylinder wall with a limited radial 'pressuresnflicient to suspendthe piston within the cylinder.

3. A resilient piston comprising; a head having piston ring grooves uponperiphery. a skirt having a eireulnferentially intact lower end section.two pair of lateral through slots in spaced planes between the head andthe lower skirt section, two radially resilient sections between thelateral slots and two semi -eircnlar ring-sections integral with thewrist pin bosses, said semi-c'ircnlar ring-sections being locatedsnbstanti alh' midway between the lateralslots, 4. The conibination of aresilient piston provided with two slotted skirt sections respectivelycomprising a plurality of spring bars integral with the skirt and witheach other, two semi-circularring sections integral with the wrist pinbosses. forniing two semicircular channels between the ring sections andthe skirt and twoeorrugated semi-circular springs, seating within thesemi-circular channels to yieldably expand the two slotted sections.

5. A piston coinprisinga tubular body provided with oppositely disposedresilient sections adapted to be independently expanded to formconcentric parallel semi-circles.

6 A piston eomprisingva tubular body provided with oppositely disposedresilient sections adapted to be independently expanded to formconeentrioimrallel semi-circles and resilient nea'nsdisposed'iiisideofthe body for expanding the resilient sections.

C O'NSTANTINE iMELIDONI.

